Will Trump Make Vaccines Another Partisan Issue?

Robert F. Kennedy Jr. talks with reporters in the lobby of Trump Tower in New York on Tuesday after meeting with President-elect Donald Trump.

Evan Vucci / AP

Robert F. Kennedy Jr., radio host, environmental lawyer and nephew of President John F. Kennedy, told reporters on Tuesday that President-elect Donald Trump has asked him to be chairman of a commission on vaccines and scientific integrity. Kennedy has repeatedly said he believes in the widely discredited claim that vaccines cause autism. (They do not.)

It’s not clear that Kennedy will get the job or that the commission will be created. After Kennedy’s statement, the Trump transition team said that while Trump is exploring the possibility, no final decisions had been made. But medical experts immediately denounced the possibility, saying it could put children in danger, and as The Washington Post put it, putting Kennedy in charge of such a commission would be a “stunning move [that] would push up against established science, medicine and the government’s position on the issue.”

Beyond the disregard for scientific evidence, however, Trump’s decision to take up vaccine-related conspiracy theories could have the added effect of polarizing opinion on vaccines along partisan lines.

Vaccines now have wide, bipartisan support: Most Americans agree with the scientific consensus that they are safe. In a YouGov survey conducted last month, 72 percent of Democrats, 67 percent of independents and 71 percent of Republicans said it was not true that vaccines caused autism. Previous surveys also showed that the vast majority of Americans (of all political stripes) agreed that children should be required to get vaccinated and should not be allowed into school until they do.

But we live in polarized times, and there have been a few issues recently that — once ushered into the political limelight — have lost bipartisan support. Democratic and Republican opinion on Russia, for example, used to rise and fall in unison. But since Russia’s meddling in the 2016 election has become an issue, and Trump has said nice things about Russia and its president, Vladimir Putin, Republicans have started to see Russia substantially more favorably than Democrats do.

Something similar happened with the Electoral College. Trump’s victory, even though he lost the popular vote, has shifted opinions on that topic as well.

The current gap between Democrats and Republicans on whether the United States should decide presidential elections by popular vote — 50 percentage points — is the largest on record.

History also tells us that scientific issues can become polarized along partisan lines and stay that way. Back in 1998, 48 percent of Republicans and 47 percent of Democrats said that global warming had already begun, according to a Gallup survey. By 2007, after a decade of fighting between Democrats and Republicans on the issue — as well as the release of “An Inconvenient Truth” starring Al Gore — 70 percent of Democrats believed climate change had started. Republican belief in global warming remained relatively steady at 45 percent. Today, even fewer Republicans (40 percent) and even more Democrats (77 percent) believe climate change has already begun.

We’re not sure that vaccines will become polarized along partisan lines. It’s not even clear to what extent Trump will take up the issue. But if he does, don’t be surprised if Republican and Democratic views on vaccines begin to diverge, even as the science stays the same.

Harry Enten is a senior political writer and analyst for FiveThirtyEight. @forecasterenten